There are different ways to take it.

There's the Kerbal Space Program approach, where space exploration is tough and you need to learn a LOT to succeed at it. The tradeoff of this is a high sense of accomplishment, where simply landing and returning from another body feels like you did something incredible.

There's also the Outer Wilds approach, where the story carries it. Moving around isn't hard at all, but you have specific goals to accomplish that move you towards a final ending. Diversity in how you accomplish those goals makes it feel fresh.

Mass Effect is similar, where you have some freedom to explore, but it's again in the pursuit of this broader story. So exploration feels like a rich side quest more than the main point of the task.

Depends on which they want more. True space or true game.

Rick and Morty. Procgen surfaces but a human story under every furniture-aliens-sit-on-humans multiverse.

Or alternatively Scavengers Reign

Personally I want spelljammer. Baldurs Gate meets Sea of Thieves in space with 80s killer clowns

There is so much drama that can happen there and the scale is the least of it.